Print-out silver halide emulsions capable of being chemically developed and/or photodeveloped



United States Patent PRINT-OUT SILVER HALIDE EMULSIONS CAPA Int. or. case 1/34 US. Cl. 96-87 Claims ABSTRACT OF THE DISCLOSURE A silver halide emulsion containing silver halide grains formed in the presence of trivalent metal ions, said silver halide system having a halogen acceptor contiguous to said trivalent metal containing silver halide grains. In one aspect, the emulsions can be used as good print-out emulsions and can be chemically developed. In another aspect they can be utilized in a photodevelopment process.

This application is a continuation-in-part application of our copending applicaton Ser. No. 481,927 filed Aug. 23, 1965, and also a continuation-in-part of our copending application Ser. No. 550,119 filed May 16, 1966.

This invention relates to radiation-sensitive silver halide materials. In one aspect this invention relates to silver halide materials which form stable visible images either by means of conventional photographic chemical development after exposure (i.e. developing-out system), directly by exposure to light (i.e. print-out system), or by exposure to light to form a latent image which can thereafter'be photodeveloped (i.e. direct-print system). In another aspect this invention relates to a silver halide material which can be chemically developed, but which can be exposed to light to form a latent image, heated to high temperatures to repress subsequent photodevelopment of the non-exposed areas and photodeveloped to produce a stable direct-print record.

With the conventional developing-out photographic system, as the name implies, the exposed material is chemically developed, fixed and washed. While this type of material yields a stable, visible image and has high sensitivity, it exhibits a low propensity for the formation of print-out images.

The print-out type of material does not require a chemical development step and may or may not be chemically fixed to yield stable, visible images. Such materials are, however, generally slower than developingout materials and exhibit poor image stability. Recently, photodevelopable direct-print materials have been designed Which do not require a chemical development step and which are of considerably higher speed than conventional print-out materials. Materials of this latter type can be chemically processed under special conditions to yield stable images but are not chemically developable with ordinary developers since the components therein tend to produce high fog levels.

It has thus far been necessary, therefore, to prepare separate photographic silver halide emulsions for use as either a developing-out material, a print-out material or I direct-print material requiring the user to stock one or more of each of these materials depending upon his requirements.

3,447,927 Patented June 3, 1969 ICC It is an object of this invention to provide novel radiation-sensitive silver halide systems that can be used to prepare visible images directly by exposure to light.

It is another object of this invention to provide novel radiation-sensitive silver halide systems that can be chemically developed.

It is still another object of this invention to provide novel radiation-sensitive silver halide systems that can be utilized as either developing-out materials or printout materials.

It is likewise an object of this invention to provide novel silver halide systems that can be utilized in a photodevelopment process.

It is also an object of this invention to provide novel silver halide emulsions useful for preparing photographic proofs.

These and other objects of the invention are accomplished with a radiation-sensitive silver halide system containing unfogged silver halide grains formed in the presence of a trivalent metal ion in an acidic media, such silver halide system having contiguous to the trivalent metal-containing silver halide grains a halogen acceptor.

In accordance with the invention, trivalent metal ions are used in the precipitation or formation of the silver halide. Silver halide crystals are formed with trivalent ions on the inside of the crystals, i.e., silver halide crystals are formed with trivalent metal ions occluded therein. Typical suitable trivalent metal ions include those of antimony, bismuth, arsenic, gold, iridium, rhodium and the like. The trivalent metal ion can be suitably added with the water-soluble silver salt (e.g., silver nitrate) or the water-soluble halide (e.g., sodium or potassium iodide, bromide or chloride) that are conventionally reacted to prepare or precipitate photographic silver halide. Likewise, the trivalent ions can be introduced into the silver halide precipitation vessel with a hydrophilic colloid such as gelatin. The trivalent metal ions can be added to the system as water-soluble inorganic salts, as organoqnetallic materials, as complexes, or any other form of material that results in the availability of trivalent metal ions during the formation of the silver halide. When the precipitation medium contains gelatin or some other reducing agent, metal ions of higher valency which are reduced to the trivalent state in the precipitation medium can be utilized to supply the trivalent metal ions. The amount of trivalent metal utilized can be widely varied, although at least about 1X l0 and more generally 1X10 to 2, mole percent based on the silver halide is used.

In preparing the silver halide used in the invention, the water-soluble silver salt and the water-soluble halide are reacted to precipitate the silver halide preferably under acidic conditions. The pH of the silver halide precipitation is typically less than 6 and preferably less than 5. Such acids as phosphoric, trifluoracetic, hydrobromic, hydrochloric, sulfuric and nitric are typically utilized in the silver halide precipitating media to maintain acidic conditions. The silver halide grains useful in the invention generally have an average grain size of about .01 to 10 microns, and more generally about .05 to 2 microns, in diameter.

Suitable silver halides include silver chloride, silver bromide, silver bromoiodide, silver chloroiodide, and silver chlorobromoiodide. The silver halide preferably contains at least 50% bromide, less than 10% iodide and less than 50% chloride on a molar basis. Both silver halide that forms latent images predominantly on the surface of the silver halide crystal or those that form latent images predominantly inside the silver halide crystal, such as those described in Davey and Knott, US. Patent 2,592,250 issued April 8, 1952, can be used in the materials of the present invention.

The silver halide of the present photographic system is typically utilized in an emulsion or dispersion containing a colloidal material. Gelatin is preferably used as the colloidal material, although other colloidal materials such as colloidal albumin, cellulose derivatives or synthetic resins, for instance, polyvinyl compounds can also be used. Hydrophilic colloids which can be used are polyvinyl alcohol or hydrolyzed polyvinyl acetate as described in Lowe US. Patent 2,286,215 issued June 16, 1942; a far hydrolyzed cellulose ester such as cellulose acetate hydrolyzed to an acetyl content of 19 to 26% as described in US. Patent 2,327,808 of Lowe and Clark, issued Aug. 24, 1943; a water-soluble ethanolamine cellulose acetate as described in Yutzy, US. Patent 2,322,085, issued June 15, 1943; a polyacrylamide or an imidized polyacrylamide as described in Lowe, Minsk and Kenyon, US. Patent 2,541,474 issued Feb. 13, 1951; copolymers (alone or in admixture with another colloid, e.g., gelatin) of an alkyl acrylate, e.g., ethyl or butyl acrylate, and acrylic acid, such as those described in Houck et al. US. Patent 3,062,674, issued Nov. 6, 1962, and Houck et al. US. application Ser. No. 139,313, filed Sept. 19, 1961; zein as described in Lowe US. Patent 2,563,791, issued Aug. 7, 1951; polymers prepared by interpolymerizing acrylic acid, an unsaturated carboxylic acid ester and a sulfo betaine as described in copending Dykstra et al. application Ser. No. 449,879, filed April 21, 1965; polymers prepared by interpolymerizing at least two monomers, one of which is a sulfoester of an alpha-methylene carboxylic acid as described in copending Dykstra application Ser. No. 454,683, filed May 10, 1965; or polymeric material which results from polymerizing a protein or a saturated acylated protein with a monomer having a vinyl group as described in US. Patent 2,852,382 of Illingsworth, Dann and Gates issued Sept. 16, 1958. Mixtures of such dispersing agents in a wide range of proportions can be utilized, typical of such mixtures being mixtures of gelatin and an acrylate-acrylic acid copolymer. Such emulsions can contain conventional addenda such as coating aids, plasticizers, sensitizing dyes, hardeners, etc. Also, minor proportionate amounts of alkali metal iodides can be eflicaciously added to the subject emulsions just prior to coating.

In additon to silver halide emulsions, vacuum deposited photographic silver halide substantially free of conventional vehicles, binders or dispersing agents can be used in the invention. Such vacuum deposited silver halide can be utilized in accordance with the invention by incorporating the halogen acceptors in a coating or layer contiguous to the vacuum deposited light-sensitive material.

The silver halide utilized in the present instance is unfogged. Such silver halide contains no visible or developable latent image. The silver halide is sensitive to electromagnetic radiation such as electrons, light and X-ray.

A wide variety of halogen acceptors can be utilized in practicing the invention. Such materials are 'well known to those skilled in the photographic art and are conventionally added to light-developable, direct-print silver halide emulsions.

Nitrogen-containing halogen acceptors are particularly useful in the invention. Suitable nitrogen-containing halogen acceptors used in the invention can be represented by the formulas,

wherein: R, R and R can each be hydrogen atoms, alkyl radicals, aryl radicals, including substituted alkyl and aryl radicals, or acyl radicals (e.g.,

I 4 wherein R is a hydrogen atom, an alkyl radical or an aryl radical); R can be a nitrogen-containing radical such as an amino radical or a thiocarbamyl radical, including substituted amino and thiocarbamyl radicals; and D represents the necessary atoms to complete a heterocyclic nucleus generally having 5 or 6 atoms including at'least two nitrogen atoms and at least one divalent radical having the formula,

wherein X can be a sulfur atom, an oxygen atom, a selenium atom or an imino radical (=NH). When a nitrogen atom is included in D or R and such nitrogen atom is attached directly to the nitrogen atoms of the above formulas, at least one hydrogen atom is attached to at least one of such nitrogen atoms of the halogen acceptor. The amino radical for substituent R can be represented by the formula,

wherein R and R can each typically be such substituents as hydrogen atoms, alkyl radicals, aryl radicals or acyl radicals as described above for R and R The thiocarbamyl radical for substituent R can be represented by the formula,

S R1 ll -CN wherein R and R can be the same substituents as R and R or amino radicals.

Particularly useful nitrogen-containing halogen acceptors used in the invention can be further represented by the following subgeneric formulas:

wherein: R R R R R R R R R and R can each be hydrogen atoms, alkyl radicals, aryl radicals or acyl radicals as described above for R and R E can be a sulfur atom, an oxygen atom, a selenium atom or an imino radical; and Q and Z can be the necessary atoms to complete a heterocyclic nucleus generally having 5 or 6 members. Q and Z typically are the necessary atoms to complete such moieties as a triazole-thiol, a' mercaptoimidazole, an imidazolidinethione, a triazine-thiol, a thiobarbituric acid, a thiouracil, a urazole including a thiourazole and the like heterocyclic moieties.

With respect to the above formulas of nitrogen-containing halogen acceptors: the aryl radical substituents are those of the naphthyl and phenyl series, and include such common substituents as alkyl groups, halogen atoms, acyl radicals and the like; the alkyl radical substituents typically can contain 1 to 20 carbon atoms and more generally 1 to 8 carbon atoms, and can be substituted with such radicals as aryl radicals, halogen atoms, acyl radicals and the like.

Typical halogen acceptors of the thiourea type represented by Formula A and Formula B are disclosed in a copending application, now Kitze US. Patent 3,241,971 issued March 23, 1966; and in copending Fix application, U.S. Serial No. 338,605, filed January 20, 1964. Typical halogen acceptors of the hydrazine type represented by Formula C are disclosed in Ives, US. Patent 2,588,982, issued March 11, 1952. Typical halogen acceptors of the type represented by Formula D are the urazole and thinurazole halogen acceptors disclosed in Bacon and Illingsworth application, U.S. Serial No. 406,186 filed October Examples of specific nitrogen-containing halogen acceptors that are useful in the invention are set out below.

1,3-dimethyl-2-irnidazolidinethione 2-imidazolidinethione 1-phenyl-5-mercaptotetrazole Thiosemicarbazide Tetramethylthiourea p-Dimethylaminobenzaldehyde'thiosemicarbazone 1-isopentyl-2-thiourea 1(Z-diethylaminoethyl)-1,2,5,6-tetrahydro-1,3,5-triazine- 4-thiol 1,2bis( 1,2,5 ,6-tetrahydro-1,3,5 -triazine-4-thiol) ethane 1-phenyl-2-thiourea 1,3-diphenyl-2-thiourea 4-thiobarbituric acid Z-thiouracil l-acetyl-Z-thiourea 1,3-dibenzyl-2-thiourea 1,1-diphenyl-2-thiourea l-ethyl- 1- alph a-n aphthyl) -2-thiourea Z-mercaptoimidazole S-selenourazole Hydrazine Phenylhydrazine hydrochloride 2,5-dichlorophenyl hydrazine 1-phenyl-2-imidazolidinethione 4,5-diphenyl-4-imidazolidine-Z-thione 1-methy1-2-mercaptoimidazole l-n-butyl-1,2,5,6-tetrahydro-1,3,5-triazine-4-thiol p-Toluene sulfonyl hydrazine Hexylhydrazine 'Ihiourea 1-methyl-2-imidazolidinethione D-mannose thiosemicarbazone Morpholino-Z-propane thiosemicarbazone D-galactose thiosemicarbazone Urazole 3-thiourazole 3 ,5 dithiourazole 3,5-dithiourazole hydrazine salt 4-aminourazole hydrazine salt 3,5-dithiourazole hydrazine salt Urazole sodium salt 4- 1-naphthyl)urazole 4-ethylurazole l-phenylurazole 4-phenylurazole l-butylurazole l-octylurazole 4-butyl-3,5-dithiourazole 1,4-diphenylurazole 1,4-dibutylurazole 1,4-dibutyl-3,S-dithiourazole 1,4-diphenyl-3,S-dithiourazole l-ethyl-4-phenylurazole 1-ethyl-4-phenyl-3,S-dithiourazole 3-thio-5-iminourazole p-Tolylhydrazine hydrochloride alpha-Naphthylhydrazine alpha-Benzyl-alpha-phenylhydrazine Such ureas, which include thioureas, urazoles, etc., as well as cyclic forms thereof, are merely illustrative halogen acceptors.

Other typical halogen acceptors that can be used in the invention include stannous salts such as stannous chloride as disclosed in Hunt, US. Patent 3,033,678 issued May 8, 1962; aromatic mercaptans such as thiosalicylic acid; hydroquinones such as hydroquinone, chlorohydroquinone, gentisic acid and t-butylhydroquinone; catechols such as phenyl catechol and t-butylcatechol; p-aminophenols such as N-methyl-p-aminophenol sulfate; 3- pyrazolidones such as 1-phenyl-3-pyrazolidone, 4-methyl- 1-phenyl-3-pyrazolidone and l-phenyl-4, 4-dimethyl-3- pyrazolidone; phenylenediamines; nitriles; phenols; glycine; sodium sulfite; alkaline material such a borax, alkali metal hydroxide, etc.; and the like halogen acceptors Well known to those skilled in the art.

The concentration of halogen acceptor utilized in the emulsions of the invention can be Widely varied in accordance with usual practice. Usually, about .01 to mole percent, and more generally about .1 to 25 mole percent, based on the silver halide in the emulsion is utilized.

The halogen acceptors are utilized contiguous to the silver halide in the present photographic system. Such halogen acceptors can be incorporated in the same photographic layer as the silver halide such as in the same emulsion layer, or in a layer adjacent to the silver halide.

The photographic silver halide system of the invention can comprise layers coated on a wide variety of supports in accordance with usual practice. Typical suitable supports include paper, polyethylene-coated paper, polypropylene-coated paper, cellulose acetate film, polyvinyl 'acetal film, polystyrene film, polyethylene terephthalate film, and related films of resinous materials, as well as glass, metals and others.

We have found that silver halide grains formed in the presence of trivalent metal cations, when coated with a halogen acceptor yield highly sensitive materials which can be utilized to advantage as either print-out materials or as developing-out materials. The high sensitivity of our materials coated with a halogen acceptor is especially surprising since many of the trivalent metal cations useful in the invention are known to powerfully desensitize silver halide photographic emulsions. For example, bismuth was shown to be a powerful desensitizer of photographic silver halide emulsions by Y. Malenowski et al. in Bulg. Ajad. Sci. Izvestia p0 Fixiko-Khema, 2, 1962, pp. 219-228 and rhodium has been noted to powerfully desensitize photographic silver halide emulsions by P. Glafkides in the English edition of Photographic Chemistry, Volume 1, 1958, p. 318.

The unexpected characteristics exhibited by our photographic silver halide system lends itself very readily to the formation of photographic proofs. When a silver halide emulsion prepared as described herein is coated with a halogen acceptor, the print-out image is unstable to further over-all exposure. However, if the halogen acceptor is removed by washing or by treatment with an oxidizing agent such as bromine water, acidic permanganate, sodium hypochlorite, N-bromosuccinimide, etc. after imagewise print-out exposure, a highly stable record is obtained. Alternatively, any method of imagewise halogen acceptor formation in the element followed by overall light exposure also gives a stable record if the silver halide emulsion layer was coated without a halogen acceptor. In either case, image fading does not occur with continued exposure.

The extremely low photographic sensitivity in the absence of a halogen acceptor, coupled with the high susceptibility to print-out in the presence of a halogen acceptor were quite surprising.

The present silver halide systems can also be utilized as light-developable materials, particularly those composed of fine-grain silver halide having an average grain size of less than about .2 micron and typically about .01 to .2 micron, and particularly those silver halide grains formed in the presence of bismuth ions. A suitable light-development process is described in copending Colt application Ser. No. 481,918 filed Aug. 23, 1965. In such a photo development application, the silver halide coating is irnagewise exposed to form a latent image, the exposed coating heated to at least about 300 F., and after heating the coating is uniformly exposed to light for a time sufiicient to produce a visible image. The heating step in such a photodevelop-ment process represses the usual printing out of unexposed or non-image areas (D the original recording sensitivity of the silver halide being inactivated by such heating. Directprint images thus prepared have a high degree of permanence or stability to ambient light.

The present silver halide systems can be effectively utilized to provide immediate transparencies which can be projected on a screen. In this embodiment the silver halide emulsions are coated on atransparent support having good dimensional stability at temperatures above 300 F. The resulting element can be processed according to the process of copending Colt application Ser. No. 481,918, filed Aug. 23, 1965, to provide a good transparency.

The transparency can be formed by heating the photographic element to temperatures of above 300 F. by the process generally disclosed in Colt. Good results are obtained in this process when the film support of the photographic element has a heat distortion temperature of at least 160 C. in both the length and width directions of said support; heat distortion temperatures are calculated according to ASTM-D-1637-6l. In the preferred embodiments superior results are obtained when a transparent film support is used which has a heat distortion temperature of at least 180 C. in both the length and width directions. Typical supports which can be used are the heat set polyesters, for example polyethylene terephthalates, cyclohexylenedimethylene terephthalates, for example, as disclosed in Kibler et al. US. Patent 2,901,- 446 issued Aug. 25, 1959, and the like; high temperature polycarbonates, for example, polycarbonates such as disclosed in copending application Ser. No. 292,139 by Caldwell and Jackson filed July 1, 1963, and the like; 1

high temperature polyimides, for example those disclosed in Chemical and Engineering News, Aug. 24, 1964, pp. 24-25, and the like. In particular, typical high temperature commercial supports useful in construction of the element are Kodak T-16 polyester, Kodak K-l polycarbonate, Du Pont Kapton Type H polyimide, Kodak Estar polyester and the like.

The following examples illustrate preferred ments of the invention.

embodi- Example 1 A radiation-sensitive gelatino silver chlorobromide mole percent chloride and 95 mole percent bromide) photographic emulsion having an average silver halide grain size of about adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halides to an agitated aqueous gelatin solution at 60 C. at a pH of about 2.0 adjusted with nitric acid. This emulsion served as a control. A second emulsion is prepared in a similar manner but differs in that the aqueous gelatin solution contains 122 mg. of bismuth nitrate pentahydrate per silver mole. Each of these emulsions are split into two portions. One portion is coated on a photographic paper support with no further addenda. The other portion is treated with 5.0 mole percent of the halogen ac ceptor dithiourazole hydrazine salt, based on the silver before coating on a similar support. Samples of each of these coatings are given an exposure of approximately 12,500 foot-candle-minutes to cool white fluorescent illumination. The reflection densities obtained, as read through a Wratten filter, are as follows:

Halogen acceptor o Control +Bi(NO3)s.5I-I20 Control +Bi(NO3)3.5HzO

.8 micron is prepared by slowly 8 Example 2 Several photographic emulsions of the type described in Example 1 are prepared. The emulsions differ only in that they contain varying levels of triammonium rhodium hexachloride described 'below in lieu of bismuth nitrate. Each of these emulsions is split into two portions and treated with the same quantity and type of halogen acceptor described in Example 1. The following data are obtained upon exposure as described in Example 1.

Halogen Feature (mg/Ag mole) acceptor Density 0. 24 0. 70 O. 15 o 1. 00 Control +(NH )aRhCla 5.0 mg 0.07 o Yes-. 1. 13 Contfol +(NH-1)3RhCls 25.0 mg N0- 0. 03 D o Yes 1. 28

Example 3 Several emulsion samples similar to those described in Example 1 but of a fine-grain size (about .06 micron) and containing the levels of gold, arsenic and antimony salts described below in place of the bismuth nitrate pentahydrat'e are prepared. Each of these emulsions is split into two parts and treated with halogen acceptor and exposed as described in Example 1 to yield the following results.

Halogen Feature (mg/Ag mole) acceptor Density Control No 0. 04 Do 0. 06 Control +KAuCl4 1 0 m 0. 00 o 1. 05 Control +KAuCl4 5.0 m 00 o 14 Control +As2O 250.0 mg 0. 03 0 Yes 1.00 Control +Sb203 250.0 mg N 0. 03 Do 1. 03

Example 4 per silver mole was added as a coating addendum along with the halogen acceptor instead of co-precipitating it with the silver halide grains. Upon exposureas described in Example 1, a density of 1.09 is obtained for this emulsion.

Example 5 Silver halide grains of the type described in Example 1 are co-precipitated with 5 mg. of Bi(NO '5H O per silver mole. An emulsion thus prepared is found to be so stable to light that several days exposure to 60 footcandles of light are required to produce detectable printout density. When a sample of this emulsion is coated with a halogen acceptor like dithiobiurea, however, it prints out rapidly to a density of about 1.2. Similar results are obtained when 10 mg. of KgIrCl per silver mole are substituted for the bismuth salt.

Example 6 Image formation in wet development experiments exhibits similardependence on the presence of a halogen acceptor. Samples of an emulsion similar to the one described in Example 1 prepared, exposed and processed as described below yield results listed in the table below.

Kodak D-72 developer, 1:1, 60 Halogen see., No. of max. acceptor Exposure visible steps (above fog) No Low intensity 1 Extremely low Yes -do 13 High (1.5

30 second exposure in a Kodak Verifax Regent Printer.

Example 7 Example 8 A coarse grain gelatino silver bromoiodide (98 mole percent bromide and 2 mole percent iodide) photographic emulsion (average grain size about 1.5 micron) is prepared by slowly adding an aqueous solution of silver nitrate 'to an aqueous gelatin solution containing the water-soluble halides, potassium iodide and sodium bromide, adjusted to a pH of 3.0 with citric acid. The water-soluble halide solution also contains 267 mg. of bismuth nitrate pentahydrate per silver mole. When samples of this emulsion are coated on photographic paper supports with and without a halogen acceptor and tested as described in Example 1, the samples without a halogen acceptor do not form a visible image during print-out whereas the samples containing 'a halogen acceptor rapidly print out to form visible images of high density.

Example 9 Three emulsions are prepared in a manner similar to that described in Example 8 but with the following variations:

(1) Pure gelatino silver bromide, precipitation pH 4.0, halide solution contains 267 mg. of bismuth nitrate pentahydrate per silver mole.

(2) Pure gelatino silver bromide, precipitation pH 3.0, halide solution contains 2.0 grams of bismuth nitrate pentahydrate per silver mole and 2.0 grams of the thioether silver halide solvent, 3,6-dithia-l,S-octanediol.

(3) Pure gelatino silver chloride, precipitation pH 3.0, halide solution contains 2.0 grams of bismuth nitrate pentahydrate per silver mole.

When the above emulsions are coated on photographic paper supports with and without halogen acceptors and tested as described in Example 1, they exhibit results similar to those described in the above examples, i.e., when compared under identical exposure conditions the samples coated without a halogen acceptor do not produce a visible print-out image whereas the samples coated with a halogen acceptor rapidly print out to form images of high density.

Minor variations in the elements of our invention readily lend themselves to various photographic applications such as documentary copying, planographic printing, transfer processes and the like. The following examples merely illustrate the variations possible and are not designed to limit them in any manner.

Example 10 Dispersion A.To 40 grams of melted paratfin is added 10 grams of the halogen acceptor, l-n-butyl-1,2,3,6- tetrahydro 1,3,5-triazine-4-thiol. The melted parafiin containing the halogen acceptor is then added to 100 ml. of a 10% aqueous gelatin solution containing 10 ml. of a 7% aqueous solution of sodium diisopropylnaphthalene sulfonate as a dispersing agent. The gelatin solution is heated above the melting temperature of the paraffin. The mixture is then stirred at high speed in a Waring Blend'or for two minutes. A finely divided dispersion of paraflin-halogen acceptor in gelatin results. A gelatino silver chlorobromide emulsion of the type described in Example 1 is coated without a halogen acceptor on a film support. Over this silver halide layer is applied Dispersion A described above as a continuous layer. This element does not produce discernible density when exposed to normal ofiice illumination of about 60 footcandles for a period of about six hours. A sample of the two-layer element is then contacted with a typewritten copy and both sheets are exposed to infrared radiation at about 150 F. for about 30 seconds (a 3M Secretary at a speed of 7-8 also being suitable). The sheets are then separated and a positive image of the typewritten copy is visible. The letters of the typewritten copy absorb enough infrared radiation to melt the wax in those areas releasing the halogen acceptor to migrate imagewise to the contiguous silver halide activating it and causing it to print-out rapidly in those areas. The image areas are hydrophilic with respect to the background areas which still contain the hydrophobic wax layer. This exposed element can then be placed on a lithographic press and copies printed, ink being carried by the unexposed oleophilic image areas. The printed images correspond to the reverse of the silver proof.

In Example 10, a positive-to-positive silver image is obtained but the ink image obtained is negative to the original positive. A system wherein both a silver and and an ink positive image may be obtained is described in Example 11.

Example 11 A wax dispersion similar to Dispersion A in Example 10, wherein beeswax is substituted for the paraffin, is coated as a continuous layer on a paper support. To the silver halide emulsion described in Example 10 is added grams of diatomaceous earth (Microcell C, Johns-Manville Company), and then coated over the wax-halogen acceptor layer. The dry, white opaque ap: pearing coating is insensitive to normal ofl'ice-illumination for an extended period of time. When thermographically exposed as described in Example 10, however, a positive silver print-out image of high density is rapidly obtained. When the exposed sample, containing the positive silver proof, is placed on a lithographic press and copies printed, ink is carried in the same areas producing positive ink images. The Microcell C par ticles are neither hydrophilic nor hydrophobic but apparently act as channels by which the constituents of the hydrophobic underlayer on melting, i.e., by thermographic exposure, migrate imagewise into the hydrophilic surface where they maintain their hydrophobic character producing a surface which is oleophilic in the image areas.

Example 12 The elements of our invention also lend themselves to multiple copy colloid transfer systems by the use of a two-layer element wherein the halogen acceptor is kept distinct from a silver halide overlayer of the type described in Example 10 but wherein a heat-degradable binder, e.g., low quality gelatin, is utilized as the vehicle but is thermographically releasable. The unexposed material is quite insensitive to normal oflice illumination and can be readily stored therein. When making copies, the element is placed in contact with the material to be copied and exposed with infrared light. This exposure releases the halogen acceptor imagewise causing the contiguous silver halide grains in those areas to rapidly print out and at the same time alters the nature of the binder in those areas. The imagewise degraded gelatin can then be transferred to a suitable receiver sheet, pref- 1 l I erably a hardener-containing paper receiver. Each transfer of the colloid carries with it a portion of the silver image. If desired, the silver halide emulsion layer can also contain additional colorants such as pigments, dyes, etc.

Example 13 A radiation-sensitive gelatino silver chlorobromide (5 mole percent chloride and 95 mole percent bromide) photographic emulsion having an average grain size of about .06 micron is prepared by slowly adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halides to an agitated aqueous gelatin solution containing 122 mg. of bismuth nitrate pentahydrate per silver mole at 35 C. at a pH of about 2.0 adjusted with nitric acid. About 5.0 mole percent of the halogen acceptor dithiourazole hydrazine salt, based on the silver, is added to the emulsion and thereafter the emulsion is coated on a photographic paper support. The resulting prepared photographic element is print-out paper which can be utilized to prepared visible images without a photodevelopment or chemical development step by exposure to 'suflicient light.

A. High intensity exposure to produce visible image directly.-A print-out image is obtained by image exposing a sample of the prepared photographic element to tungsten illumination of 400,000 toot-candle seconds (5 minutes to 1380 foot-candles). A reflection density of 1.44 was produced by photolysis under roomlight conditions. An area of the same photographic element which is not exposed to light has a reflection density of 0.09. The image discrimination of the exposed photographic element is 1.35 density units (1.44-0.09)

B. Latent image exposure+heat treatment+photodevelopment to produce visible image-Another sample of the above-described photographic element is image-exposed in accordance with the invention to tungsten illumination to give an exposure of 240 foot-candle seconds seconds to 12 foot-candles). No visible image on the image-exposed photographic element is apparent. The resulting sample with an area having this latent image exposure and an area with no exposure is heated by holding it in contact with a metal platen at 530 F. for 2 seconds in the dark. The sample is then exposed uniformly to tungsten illumination to give an exposure of 400,000 foot-candle seconds to photodevelop the latent image. The area given the latent image exposure is darkened to give a reflection density of 1:1. The area receiving no latent image exposure is darkened only slightly by the exposure of 400,000 foot-candle seconds, the reflection density being 0.33. The image discrimination of this photographic element is 0.92 density units (1.25- 0.33). When the heat treatment step before the photolysis step is omitted, the entire emulsion area of the photographic element prints out to uniform density, there being no differentiation between image and non-image areas.

These data demonstrate that a density difference of the magnitude usually associated with print-out papers can be achieved in a paper given only a latent image exposure if the paper is heated to a high temperature prior to over-all photolysis.

Example 14 Two photographic elements of the type described in Example 13 and treated as described in Example 13A and Example 13B are prepared and designated Element A and Element B" in the table below.

(a) Element AVisible image prepared directly with a high intensity image exposure (a print-out image).

(b) Element BVisible image prepared by latent image exposure+heat treatment+photodevelopment (exposure in accordance with the invention).

Both Element A and Element B are exposed for 2 minutes to 1600 foot-candles of illumination from a White flame arc lamp. The reflection densities of exposed and unexposed areas (image and non-image areas) are measured before and after the arc lamp exposure.

Before arc lamp After are lamp exposure exposure Element A:

Exposed area.- 1. 44 1. 55 Unexposed area. 0.09 1. 46 Discrimination 1. 35 0. 09 Element B: Y I

Exposed area 1. 25 1. 34 Unexposed area 0. 33 0. 43 0. 92 0. 91

Discrimination The data set out in the above table illustrates the improved light stability of images processed in accordance with the invention with a print-out photographic system.

Example 15 Platen temp, Exposed Unexposed degrees F. area area D1serimination The data in the above table illustrate that heating times of one minute at temperatures of at least about 300 F. are used toachieve any significant image discrimination.

Example 16 Trivalent metal salt: Concentration (mg/Ag mole) (NH RhCl 1.0 5.0 (NH RhCl 25.0

The various emulsions are coated on photographic paper supports, and image exposed to form visible images in the areas of exposure.

' Example 17 A radiation-sensitive gelatino silver bromoiodide (94 mole percent bromide and 6 mole percent iodide) photographic emulsion having an average grain size of about .06 micron, is prepared by slowly adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halide to agitated aqueous gelatin solutions containing various concentrations of K IrCl About 5 mole percent of a halogen acceptor, dithiourazole hydrazine salt, based on the silver, is added to the emulsions. A control emulsion without a trivalent metal salt is also prepared.

The respective emulsions are coated on photographic paper support, image exposed, heated at approximately 460 F. for 6 seconds in the darle and photodeveloped in the dark and photodeveloped to form visible images in the area of exposure. A direct-print element having high image discrimination is obtained as follows.

Example 18 A silver chlorobromide emulsion mole percent chloride and 95 mole percent bromide) is prepared according to Example 17 except Bi(NO -5H O is present in the aqueous gelatin solution during precipitation. About 4 mole percent of a halogen acceptor, dithiourazole hydrazine salt, based on the silver content, is added to the emulsion.

The emulsion is coated on a high temperature, heat resistant polyethylene terephthalate support at a laydown of about 350 mg./ft.

The coating is exposed for four seconds in a contact printer through a 0.15 density increment step wedge. The strip is then placed in contact with a heat platen at about 430 F. for four seconds, after which it is photodeveloped for 5 minutes at a distance of one foot from a No. 2 reflector photoflood lamp. The resulting image has a D of 2.01 and a D of 0.38. The number of visible 0.15 log E steps is about 13. An unheated area of the emulsion produces a background density of about 2.09.

Similar results are obtained when the emulsion is coated on Kapton Type H (Du Pont) polyimide support, Kodak T-16 heat set polyester support, Kodak K1 polycarbonate and glass supports.

Example 19 A radiation-sensitive gelatino silver bromoiodide (94 mole percent bromide and 6 mole percent iodide) photographic emulsion having an average grain size of about .06 micron, is prepared by slowly adding simultaneously an aqueous solution of silver nitrate and an aqueous solution of alkali metal halide to an agitated aqueous gelatin solution containing 50 mg. of bismuth nitrate pentahydrate per silver mole at 35 C. at a pH of about 2.0. About 5 mole percent of a halogen acceptor, d-ithiourazole hydrazine salt, based on the silver, is added to the emulsion. The resulting emulsion is divided into three portions. One portion of the emulsion, referred to below as Emulsion A, is coated on a photographic paper support. A second portion of the emulsion, referred to below as Emulsion B, is spectrally sensitized with a benzothiazole2-thia-2,4-oxazolidenedione merocyanine ortho sensitizer of the type described in U.S. Patent 2,263,757 at a concentration of about 150 mg. per silver mole and coated on a photographic paper support. A third portion of the emulsion, referred to below as Emulsion C is sensitized with a dibenzothiacarbocyanine panchromatic sensitizer of the type described in U.S. Patent 2,503,776, at a concentration of about 180 mg. per silver mole, and coated on a photographic paper support. A sample of each of the coated emulsions is exposed in an intensity scale sensitometer to form latent images therein. The resulting exposed samples are thereafter heated by holding in contact with a metal platen at about 425 F. for about 2 seconds. A sample is then exposed uniformly to tungsten illumination to give an exposure of about 400,000 foot-candles seconds to photodevelop the latent images in each of the three coatings. The image discrimination, that is, the difierent in density between the image and background areas, for each of the three coatings is about 1.1. The photographic element having coated thereon Emulsion A has a relative speed of 250; the photographic element having coated thereon Emulsion B has a relative speed of 1,000 and the photographic element having coated thereon Emulsion C has a relative speed of 3,160.

The invention has been described in considerable de- 14 tail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A'radiation-sensitive silver halide system comprising a direct-print halogen acceptor and silver halide crystals formed in an acidic media with trivalent antimony. arsenic, bismuth, gold, iridium or rhodium ions occluded on the inside of said crystals.

2. A radiation-sensitive silver halide system according to claim 21 wherein the halide of said silver halide is at least 50 molar percent bromide and wherein the silver halide crystals have been formed in the presence of said trivalent ions.

3. A radiation-sensitive system according to claim 1 wherein said trivalent ions are rhodium ions.

4. A radiation-sensitive system according to claim 1 wherein said trivalent metal ions are bismuth ions.

5. A radiation-sensitive silver halide system comprising a nitrogen-containing halogen acceptor and silver halide crystals formed in an acidic media with trivalent antimony, arsenic, bismuth, gold, iridium or rhodium ions occluded on the inside of said crystals.

6. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the nitrogen-containing halogen acceptor is a thiourazole.

7. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the nitrogen-containing halogen acceptor is a thiourea.

8. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the nitrogen-containing halogen acceptor is a urazole.

9. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the trivalent ions are iridium 10118.

10. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the trivalent ions are gold ions.

11. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the trivalent ions are rhodium ions.

12. A radiation-sensitive silver halide emulsion as described in claim 5 wherein the trivalent ions are bismuth 10118.

13. A light-sensitive gelatino silver halide emulsion comprising a nitrogen-containing halogen acceptor and silver halide grains having bismuth ions occluded therein, wherein said silver halide grains are formed in an acidic media and wherein the halide of said silver halide grains is at least 50 molar percent bromide.

14. A light-sensitive emulsion according to claim 13 wherein said halogen acceptor is a urazole.

15. A light-sensitive emulsion according to claim 13 wherein said halogen acceptor is a dithiou-razole hydrazine salt.

16. A radiation-sensitive silver halide system comprising silver halide grains formed in an acidic media having trivalent metal ions on the inside of said grains, said silver halide system having a halogen acceptor contiguous to said silver halide grains, which system yields visible print-out images directly by exposure to light and can be imagewise exposed to form a latent image therein which can be chemically developed to a visible image.

17. A radiation-sensitive silver halide system comprising silver halide grains having trivalent metal ions on the inside thereof, wherein said grains have been formed in an acidic media, and a halogen acceptor contiguous to said trivalent metal ion containing silver halide grains, which system yields a stable image record when imagewise exposed, heated to at least 300 F. and then photodeveloped.

18. A radiation-sensitive silver halide system according to claim 17 wherein said silver halide grains have bismuth ions on the inside thereof.

19. A radiation-sensitive silver halide system according to claim 17 wherein said halogen acceptor is a urazole compound.

'20. A photographic element comprising a support, and a layer of a silver halide composition comprising a directprint halogen acceptor and silver halide grains having trivalent antimony, arsenic, bismuth, gold, iridium or rhodium ions occluded therein.

21. An element as described in claim 20 wherein said support is a transparent support.

22. An element as described in claim 20 wherein said support is a polyester, polycarbonate or a polyimide.

.23. An element as described in claim 21 wherein said support has a heat distortion temperature of at least 160 24. A photographic element comprising a polyester, polycarbonate or polyimide support, and a layer of a radiation-sensitive silver halide composition comprising a halogen acceptor and silver halide grains having trivalent metal ions occluded therein, wherein said grains have been formed in an acidic media; which system yields a stableimage record when imagewise exposed, heatedto'at least 300 F. and photodeveloped. 25. A photographic element according to claim 24 wherein said support has a heat distortion temperature of at least 180 in both length and width directions.

References Cited UNITED STATES PATENTS 3,241,971 3/1966 Kitze "96107 US. 01. X.R.

9/1955 Wark 96108 ygg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3, Mil? 927 Dated une 3, 1 9 9 lnventofls) Robert E. Bacon and Jean F. Barbier It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[- Column 6, columnar line 7, "a" should read -a:"-- .1

Column 7, columnar lines 31 -32, "2, 901 ,Lpl should read 2, 90! ,LL66-. Column 8, table of Example 2, under heading "Feature (mg./Ag mole) approximate columnar line 19, "Contfol" should read ---Control---. Column 10, columnar line 37, after "10, should be inserted ---but-. Column 1L columnar line 9, after "antimony", should read columnar line 13, "21 should read ---1 316MB mu SEMH) uozb e69 & I"

L Aim g Offiw 7 mm 1:. .m.

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